Blower housing



April 1966 P. F. SWENSON 3,246,8 34

BLOWER HOUSING Filed Dec. 18, 1965 2 Sheets-Sheet 1 INVENTOR. @111 ZX/W,

April 19, 1966 P. F. SWENSON 3,246,834

BLOWER HOUSING Filed Dec. 18, 1963 2 heets-She t 2 I VENTOR.

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United States Patent 3,246,834 BLOWER HOUSING Paul F. Swanson, Cleveland Heights, Ohio, assignor, by

mesne assignments, to Space Conditioning, Inc, Harrisonburg, Va., a corporation of Maryland Filed Dec. 18, 1963, Ser. No. 331,473 3 Claims. (Cl. 230-128) This invention relates to centrifugal blowers, and particularly to a new and improved scroll or casing therefor.

I-Ieretofore in centrifugal blowers with scroll casings, the air is delivered into the passage in the casing through an air inlet in the inner periphery of the casing and is discharged from the passage generally tangentially of the casing at one end. The radial dimension of the air passage increases progressively in the direction of rotation of the rotor. The air stream flowing along the passage concentrates at the outer periphery and is discharged as a stream having greater velocity and volume of flow per unit of cross section adjacent the outer peripheral wall than adjacent the inner peripheral wall. In fact, at the latter, there is often negligible flow. To produce a more nearly uniform flow of air across the duct outlet it is customary to connect to the outlet a lineal transition duct, often several feet long, of gradually increasing cross section in the direction of flow.

According to the present invention, a scroll or casing is provided wherein the air stream issuing from the casing outlet is rendered substantially uniform in pressure and volume over its entire cross section at the outlet so that a transition duct is unnecessary.

The scroll or casing is one of which not only the radial dimension, but also the axial dimension, of the air passage increases progressively in the direction of flow of air therealong, the radial dimension increasing at a greater rate than the axial dimension.

The present invention also contemplates the use of a casing and blower rotor of such design that the fully assembled rotor can readily be inserted as a unit axially in the axial passage of the scroll casing and moved to operating position therein without the removal of any auxiliary parts and without the necessity of installing auxiliary parts in the passage after insertion of the rotor therein.

An important object of the invention is to provide a scroll having an oulet with a relatively large aspect ratio, or length to breadth ratio, as compared to conventional scrolls of which the outlets are generally square or of small aspect ratio, so that the present scroll can be used with the type of heating and cooling units which generally employ a fan or blower for air circulation and of which the heat exchangers generally are long and narrow.

The present scroll makes possible the use of a single blower in many instances wherein, because of the large aspect ratio of the exchanger, dual blower fans are now required.

Another object is to combine the present casing with a mixed type of blower having blades of which the lateral margins act as propellers to draw air axially into the rotor, and of which the central portions act as centrifugal blower blades and discharge the air into the scroll or casing.

Various objects and advantages of the invention will become apparent from the following description wherein reference is made to the drawings, in which:

FIGURE 1 is a diagrammatic top plan view of a dual blower structure embodying the principles of the present invention;

FIG. 2 is a front elevation of one of the blowers illustrated in FIG. 1;

FIG. 3 is a right side elevation of the scroll or casing of the blower illustrated in FIG. 2, the rotor being omitted for clearness in illustration; and

FIG. 4 is a sectional view of the blower illustrated in FIG. 2, and is taken on line 44 thereof.

Referring to the drawings, the blower of the present invention is shown as incorporated in a dual blower wherein two identical blowers 1 are placed at opposite ends of a double end shaft electric motor 2, with rotors 3 of the blowers mounted on the end shafts, respectively. The motor 2 is mounted on the usual cushioning resilient means for damping its vibrations transversely of its axis in the usual manner of mounting rotating equipment for more quiet operation.

Though the invention is shown in a dual type blower, either blower may be used as a single blower.

Referring specifically to the blower of the present invention, the blower 1 comprises a scroll or casing 5, having an inner pheripheral cylindrical wall 6, and an outer peripheral wall 7, and side walls 8 connecting the inner and outer walls at their lateral edges. The casing has an axial passage 9 for admitting air into the rotor.

The inner wall 6 has a circumferentially extending air inlet opening 10 therein which extends equidistantly axially of the passage 9, from the axial midportion of the passage 9. The inlet opening 10 extends substantially the full length of the wall 6 and opens directly toward the outer peripheral wall 7, and the space between the inlet 10 and the outer peripheral wall 7 is unobstructed throughout the circumferential length of the inlet.

The space between the inner and outer walls is closed by the wall 12 at the ends of the walls which are in closest radial proximity to each other. The outer wall recedes progressively radially outwardly from the inner wall in the direction of rotation of the rotor. Thus the scroll defines an air discharge passage 13 extending lengthwise of the walls 6 and 7 and of progressively increasing radial dimension from the wall 12 to its outlet 14.

The rot-or 3 is mounted in the axial passage 9 in coaxial relation thereto. The rotor comprises a hub 16 mounted on a shaft 17 of the motor 2. The hub carries a radially extending disc 18 on which are blades 19, preferably of the mixed flow type. Each blade 19 has a midportion 19a which preferably is coextensive, or slightly greater, in width with the width of the air inlet opening 10. Each blade 19 has lateral margins 19b which extend endwise of the passage 9 beyond the lateral limits of the passage 10. These portions 19b are of a propeller type, that is, their forward faces in the direction of rotation curve forwardly from the central portion 19a toward the outer lateral edges of the blades, so as to act as propellers to draw air into the passage 9 and scoop it into the rotor axially toward the midportions 19a of the blades, which, in turn, then discharge it through the inlet opening 10 into the scroll passage 13. This eliminates the necessity for confining rings in the passage 9 and any type of packing, and hence assures the free rotation of the rotor. Each of the blades 19 terminates radially outwardly from the axis of the shaft 17 close to, but spaced from the inner wall 6, this operating clearance being sufiicient so that slight vibration of the motor and rotor does not cause the outer radial ends of the blades 19 to strike the wall 6. Further, since the blades 19 are unconfined at their lateral edges, slight tilting due to vibration does not cause interference with their rotation. By virtue of this arrangement, the rotor in fully assembled condition can be inserted as a unit into the passage and moved axially to operating position without disassembling any part of the blower or removing any auxiliary parts.

As mentioned, the casing is to deliver air at a relatively uniform pressure and volume across the entire cross-sectional area of the output 14, thus eliminating any need for a transition duct. For this purpose the walls 6 and 7 are made of gradually increasing widths axially of the passage 9 from the end wall 12 entirely to the outlet 14.

Patented Apr. 19, 1966';

Likewise, as mentioned, the outer wall 7 is spaced progressively farther outwardly from the inner wall 6 beginning at the wall 12 and continuing entirely to the outlet 14. The air passage 13 for receiving air from the impeller blades is of substantially rectangular cross section, increasing in length axially of the central passage 9 and also increasing in dimension radially of the central passage 9.

The rate of increase in the width of the passage 13 is relatively constant throughout the length of the passage 13 as also is the rate of increase in the radial dimension. However, these rates are not identical, the rate of increase in radial dimension being greater than the rate of increase in width; In the-form illustrated, in which the blower is slightly more than four and one-half inches in outer diameter, and the other parts in proportion, the cross sections of the passage 13', taken on line'4-4'so as to be 180 apart, are as follows:

The radial dimension of the right-hand cross section of passage 13 is about one-fourth inch, andthat of the'lefthand section is aboutthree-fourths of an inch, the increase of radial dimension in 180 being 1 0 3.

The width of the right-hand section is about two and three-fourths inches, and the width of the left-hand. section is about five inches, the ratio of width being. almost 1 to 2.

Thus the radial dimension increases at the rate of'3 to 1 and the width increases at'the rate of about 2 to 1, so that the radial dimension increases about one and one-half times as rapidly as the width. The result of this arrange ment is that the scroll or casing air passage 13' can be proportioned to the particular blower so that uniform pressure, velocity, and volumetric discharge is provided over the entire cross section of the outlet 14.

While a mixed flow combination propellar and radial discharge blower rotor is preferred, an ordinary centrifugal blower rotor =can be provided. However, insuch cases, a confining ring or annulus should be placed in the passage 9 at each end of the rotor. fining ring need be removed for purposes of inserting the rotor within the casing. A mixed flow fan is preferred because it gives the maximum inlet area for a given diameter, as it utilizes all of the passage 9, and it also operates with a minimum of noise.

Having thus described my invention, lclaim:

1. A centrifugal blower, comprising a casing having an.

inner peripheral wall defining an axial passage, an outer peripheral wall spaced radially outwardly from and Only one such conaligned radially with the inner wall, side walls connecting the inner wall and outer Wall, said inner, outer, and side walls defining an air passage extending endwise of the walls and having an outlet at one end, the spacing of the outer wall from the inner wall being progressively greater from the end of said passage opposite from the outlet to the outlet, and the Widths of said inner and outer walls being progressively greater from the end opposite the outlet to said outlet, said inner wall having an air inlet opening substantially coextensive lengthwise with the inner wall and extending laterally of the inner wall from the axial midportion of the inner wall partway toward the side walls, a rotor disposed in the axial passage in coaxial relation thereto and including a hub and a plurality of impeller blades extending. outwardly from the axis thereof, said blades extending endwise, axially of the axial passage, entirely across said air inlet opening, said impeller blades being unconfined axially of the air inlet opening and being mixed flow blades having radially extending propeller portions at their outer lateral margins operative for blowing air axially of the axial passage toward the axialmidportion'of the rotor, and having radial discharge portions between said margins aligned radially with said air inlet opening and at least substantially coextensive therewith axially of the axial passage, and a power driven shaft coaxial with and supporting said hub.

2; A structureaccording to claim 1 wherein in the direction endwise of the air passage, the spacing of the inner and outer walls increases progressively at a greater rate than the progressive increase in'the width ofthe air passag'e.

3. A structure according to claim 2 wherein the progressive increase in said spacing is one and one-half times the progressive increases in said width.

References Cited by the Examiner UNITED STATES PATENTS 1,014,321 1/1912 Minor 230134.5 1,536,306 5/1925 Nusim 230134.4 2,301,857 11/1942 Criqui 230-127 FOREIGN PATENTS 441,385 1/1936 Great Britain. 305,754 2/1933 Italy.

96,876 I 9/ 1939 Sweden.

DONLEY I. STOCKING, Primary Examiner.

HENRY F. RADUAZO, Examiner. 

1. A CENTRIFUGAL BLOWER, COMPRISING A CASING HAVING AN INNER PERIPHERAL WALL DEFINING AN AXIAL PASSAGE, AN OUTER PERIPHERAL WALL SPACED RADIALLY OUTWARDLY FROM AND ALIGNED RADIALLY WITH THE INNER WALL, SIDE WALLS CONNECTING THE INNER WALL AND OUTER WALL, SAID INNER, OUTER, AND SIDE WALLS DEFINING AN AIR PASSAGE EXTENDING ENDWISE OF THE WALLS AND HAVING AN OUTLET AT ONE END, THE SPACING OF THE OUTER WALL FROM THE INNER WALL BEING PROGRESSIVELY GREATER FROM THE END OF SAID PASSAGE OPPOSITE FROM THE OUTLET TO THE OUTLET, AND THE WIDTHS OF SAID INNER AND OUTER WALLS BEING PROGRESSIVELY GREATER FROM THE END OPPOSITE THE OUTLET TO SAID OUTLET, SAID INNER WALL HAVING AN AIR INLET OPENING SUBSTANTIALLY COEXTENSIVE LENGTHWISE WITH THE INNER WALL AND EXTENDING LATERALLY OF THE INNER WALL FROM THE AXIAL MIDPORTION OF THE INNER WALL PARTWAY TOWARD THE SIDE WALLS, A ROTOR DISPOSED IN THE AXIAL PASSAGE IN COAXIAL RELATION THERETO AND INCLUDING A HUB AND A PLURALITY OF IMPELLER BLADES EXTENDING OUTWARDLY FROM THE AXIS THEREOF, SAID BLADES EXTENDING ENDWISE, AXIALLY OF THE AXIAL PASSAGE, ENTIRELY ACROSS SAID AIR INLET OPENING, SAID IMPELLER BLADES BEING UNCONFINED AXIALLY OF THE AIR INLET OPENING AND BEING MIXED FLOW BLADES HAVING RADIALLY EXTENDING PROPELLER PORTIONS AT THEIR OUTER LATERAL MARGINS OPERATIVE FOR BLOWING AIR AXIALLY OF THE AXIAL PASSAGE TOWARD THE AXIAL MIDPORTION OF THE ROTOR, AND HAVING RADIAL DISCHARGE PORTIONS BETWEEN SAID MARGINS ALIGNED RADIALLY WITH SAID AIR INLET OPENING AND AT LEAST SUBSTANTIALLY COEXTENSIVE THEREWITH AXIALLY OF THE AXIAL PASSAGE, AND A POWER DRIVEN SHAFT COAXIAL WITH AND SUPPORTING SAID HUB. 